Soft, Tough, and Thermally Conductive Elastomer Composites by Constructing a Curled Conformation

Filled elastomer composites have gained significant attention due to their ability to undergo large-strain reversible deformations with minimal force. However, achieving the desired functionality, such as high thermal conductivity, often requires ultrahigh filler loadings (above 50%). Unfortunately, excessive filler loading compromises the softness and toughness of the composites due to the prevalence of trapped entanglements. To address this challenge, a simple solvent-thermal design strategy is reported to optimize the balance among Young's modulus, stretchability, and toughness in highly filled elastomer composites. This is realized by the curled conformation formed by the disentangling of the excessively entangled polymer chains and by better mixing of the BN filler and the polymer matrix. The released trapped entanglement can effectively reduce the Young's modulus (2.80 MPa) of the C-PDMS/60 wt % BN elastomer composites, and the strong unfolding and stretching ability of the curled conformation also endows it with excellent stretchability (∼492%), thus achieving high toughness (∼2.80 MJ m–3). Additionally, the better mixing ability allows the C-PDMS/60 wt % BN elastomer composites to be compounded with the high BN filler loading (60 wt %), thus achieving high thermal conductivity (1.65 W m–1 K–1). The comprehensive performance of the C-PDMS/60 wt % BN demonstrates remarkable advancements in highly filled elastomer composites. Leveraging these favorable characteristics, the curled PDMS/BN elastomer composites can serve as effective thermal interface materials for efficient heat dissipation and hold great potential for applications in the field of flexible electronics.